This invention relates to utility knives and, more particularly, a utility knife having an improved safety feature.
Many types of knives having readily changeable blades have been developed in the past. Representative prior art utility knives are disclosed in the following U.S. patents:
U.S. Pat. Nos. 971,257; 1,616,040; 1,877,827; 2,131,358; 2,651,108; 2,679,100; 2,788,574; 2,862,296; 3,520,059.
In prior art configurations, including some of those set forth in this listing, provision is made for mounting blades of different types and/or sizes in a given knife and, to enhance this capability, the knife may have a blade-holding mount or chuck at both ends thereof. These mounts or chucks may have different configurations and/or sizes to receive different configurations and/or sizes of blades. It is desirable that the blades be readily and quickly changeable but, at the same time, the blade in use must be firmly and securely mounted in the knife. A further consideration is that the knife mechanism not be unduly complex or expensive to manufacture.
In the type of knife wherein blades are mountable at either end, a further important consideration is safety. If a user inadvertently or intentionally mounts blades at both ends of the knife, a severe safety hazard arises. A knife with exposed blades at both ends (for example, blades of two different types) may save a moment in switching blades, but could easily cause the accidental cutting of the user or a subsequent user who does not initially realize that blades are mounted at both ends of the knife.
It is an object of the present invention to devise a utility knife which has the flexibility of allowing blades to be mounted at either end thereof using uncomplicated and reliable mounts, while providing an important safety feature which prevents the simultaneous mounting of blades at both ends of the knife.